[all-commits] [llvm/llvm-project] 3d29c4: [InstCombine] Insert instructions before adding th...

[Jakub Kuderski via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 3d29c41ad59e2e783da43a8b30a3f4f2d0c78a72
      https://github.com/llvm/llvm-project/commit/3d29c41ad59e2e783da43a8b30a3f4f2d0c78a72
  Author: Jakub Kuderski <kubak at google.com>
  Date:   2019-12-18 (Wed, 18 Dec 2019)

  Changed paths:
    M llvm/include/llvm/Transforms/InstCombine/InstCombineWorklist.h
    M llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
    M llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
    M llvm/test/Transforms/InstCombine/zext-or-icmp.ll

  Log Message:
  -----------
  [InstCombine] Insert instructions before adding them to worklist

Summary:
This patch adds instructions to the InstCombine worklist after they are properly inserted. This way we don't get `<badref>`s printed when logging added instructions.
It also adds a check in `Worklist::Add` that ensures that all added instructions have parents.

Simple test case that illustrates the difference when run with `--debug-only=instcombine`:

```
define i32 @test35(i32 %a, i32 %b) {
  %1 = or i32 %a, 1135
  %2 = or i32 %1, %b
  ret i32 %2
}
```

Before this patch:
```
INSTCOMBINE ITERATION #1 on test35
IC: ADDING: 3 instrs to worklist
IC: Visiting:   %1 = or i32 %a, 1135
IC: Visiting:   %2 = or i32 %1, %b
IC: ADD:   %2 = or i32 %a, %b
IC: Old =   %3 = or i32 %1, %b
    New =   <badref> = or i32 %2, 1135
IC: ADD:   <badref> = or i32 %2, 1135
...
```

With this patch:
```
INSTCOMBINE ITERATION #1 on test35
IC: ADDING: 3 instrs to worklist
IC: Visiting:   %1 = or i32 %a, 1135
IC: Visiting:   %2 = or i32 %1, %b
IC: ADD:   %2 = or i32 %a, %b
IC: Old =   %3 = or i32 %1, %b
    New =   <badref> = or i32 %2, 1135
IC: ADD:   %3 = or i32 %2, 1135
...
```

Reviewers: fhahn, davide, spatel, foad, grosser, nikic

Reviewed By: nikic

Subscribers: nikic, lebedev.ri, hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D71093